▎ 摘　　要

Electrical charging of Co/N-4 cluster embedded in graphene (Co/N-4/G) is proposed as an approach for electrocatalytically switchable hydrogen adsorption. Using density functional theory, we found that the H-2 molecule is weakly adsorbed on the uncharged Co/N-4/G cluster. Our results show that the adsorption energy of hydrogen molecule on Co/N-4/G cluster is significantly increased by introducing extra positive charges into the cluster. Once the charges are removed, H-2 molecule spontaneously desorb from the Co/N-4/G absorbent. Therefore, this approach promises both facile reversibility and tunable kinetics without the need of specific catalysts. Our study indicates that the Co/N-4/G nanomaterial is excellent absorbent for controllable and reversible adsorption and release of H-2. (C) 2017 Elsevier B.V. All rights reserved.